Human Molecular Genetics Advance Access originally published online on September 23, 2003
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Human Molecular Genetics, 2003, Vol. 12, No. 22 2941-2948
DOI: 10.1093/hmg/ddg319
© 2003 Oxford University Press
Mutation of a transcriptional motif of a distant regulatory element reduces the expression of embryonic and fetal globin genes
Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
Received June 26, 2003; Revised August 26, 2003; Accepted September 10, 2003
High-level ß-globin gene expression is dependent on the presence of the locus control region (LCR), a powerful regulatory element physically characterized by five DNase I-hypersensitive sites (HS), designated HS1–HS5. Of these, HS3 contains seven GT motifs that are essential for its activity. One of the motifs, GT6, has been shown by in vivo footprinting to display the largest difference in signal between fetal and adult globin expressing cells. We assessed the contribution of GT6 on the downstream globin gene expression by mutating this motif in a 248 kb ß-globin locus yeast artificial chromosome and measuring the activity of ß-globin genes in GT6m ß-YAC transgenic mice. Seven transgenic lines were established, three of which contained at least one intact copy of the ß-globin locus and were further investigated. The mutation of the GT6 motif reduced the expression of 
- and 
-globin genes during embryonic erythropoiesis. During definitive erythropoiesis, -globin gene expression was significantly reduced while ß-globin gene expression was virtually indistinguishable from wild-type controls. We conclude that the GT6 motif of hypersensitive site 3 of the LCR is required for normal - and -globin gene expression during embryonic erythropoiesis and for -globin gene expression during definitive erythropoiesis in the fetal liver. Our results provide evidence that mutations of single transcriptional motifs of distant regulatory elements can have profound effects on gene expression.
* To whom correspondence should be addressed. Tel: +1 2065433526; Fax: +1 2065433050; E-mail: gstam{at}u.washington.edu
Present address: Amgen US Medical Affairs, Thousand Oaks, CA 91358, USA.
Present address: Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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